mirror of https://github.com/python/cpython
31 lines
743 B
Python
31 lines
743 B
Python
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import collections
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# from jaraco.collections 3.3
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class FreezableDefaultDict(collections.defaultdict):
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"""
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Often it is desirable to prevent the mutation of
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a default dict after its initial construction, such
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as to prevent mutation during iteration.
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>>> dd = FreezableDefaultDict(list)
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>>> dd[0].append('1')
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>>> dd.freeze()
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>>> dd[1]
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[]
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>>> len(dd)
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1
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"""
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def __missing__(self, key):
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return getattr(self, '_frozen', super().__missing__)(key)
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def freeze(self):
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self._frozen = lambda key: self.default_factory()
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class Pair(collections.namedtuple('Pair', 'name value')):
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@classmethod
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def parse(cls, text):
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return cls(*map(str.strip, text.split("=", 1)))
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